Insect Orders (2): Moths and Butterflies (Lepidoptera)
Above: Many butterflies have pretty odd names, such as this Peacock Pansy, Junonia almana javana.
Introduction
On a sunny morning, it is not uncommon to spot fluttering butterflies soak up the morning sun and seek nectar from flowers. Their bright colours, along with their graceful and deliberate movements, endear themselves to many humans, especially kids. And they are often one of the few insects that do not generate disgust or fear among humans. It is thus somewhat enigmatic to me that moths, which are actually very similar to butterflies and are not even distinctly separate from butterflies in terms of phylogenetics, are feared by many humans. Moths are actually more numerous, species wise, than butterflies. Together, they are known as Lepidopterans, which translates to "scale wings", due to the tiny scales that do in fact make up their wings. Many adult Lepidopterans have a proboscis, which they use to suck up sugar-rich meals, such as nectar and rotten fruit. The larvae (more commonly known as caterpillars) are usually herbivorous, with chewing mouthparts, although carnivorous ones exist.
Life cycle
Like beetles (Coleoptera) and flies (Diptera), the butterflies and moths are holometabolous, and go through complete metamorphosis. Eggs hatch into caterpillars which feed voraciously on leaves. Most grow to many times their original size in a short span of time, after which they pupate into cocoons (moths) or chrysalises (butterflies). In their pupal stage, they are often immobile and may seem lifeless. However, inside the pupa the body of the caterpillar is undergoing rapid and drastic changes, with the most notable development being the scaly wings that a quintessential Lepidopteran boasts. When the adult finally emerges, it has to dry it wings and prepare to take flight. The adult Lepidopteran is often short-lived, with its main purpose being to seek a mate and procreate. As such, there are many moths and butterflies who do not feed at all in their adult stage.
The larvae of Lepidopterans often have no more than 5 pairs of prolegs, which are appendages that aid in movement, but are not true legs. This can help in distinguishing them from the strikingly similar sawfly larvae, which have more than 5 pairs of prolegs.
Above: Chalciope mygdon, the Triangular moth. Pretty cool huh?
"Moth" vs "Butterfly"
Lepidopterans are often seen as two different groups by the layman: Moths and butterflies. While genetically very similar, the Lepidopterans that are considered moths do have certain profound differences compared to those which are called butterflies.
Butterflies are often thought to be more brightly coloured than moths. While that may be true in most cases, colourful moths do exist, and drab butterflies are not rare either. Next, butterflies may be seen as diurnal, with moths being their nocturnal counterparts. This is not exactly a good way to tell them apart, as day-flying moths are known to occur, such as the Sunset moths (Uraniidae). While many butterflies rest with their wings upright, and moths with their wings opened, this comparison has many exceptions, and is thus not a very reliable way to tell them apart.
More reliable methods to tell them apart based on morphology include looking at their antennae and abdomen. Moths tend to have feathery (in the males of many species) or thread-like antennae, while butterflies have clubbed antennae. However, exceptions are still present for this rule, with the Uraniidae possessing clubbed antennae for example. As for the abdomen, moths tend to be hairier than butterflies.
Above: Moths can have pretty attractive colourations too, like this Lichen moth of the family Erebidae.
Diet
Most Lepidopterans source their food from plants. The adults feed mainly on nectar and other sugar-rich liquids like fruit juice. The caterpillars are mostly herbivorous, feeding on leaves of various plants. Some are known to feed on only one species of plant, while many are polyphagous and feed on several species of plants. Moth caterpillars tend to exhibit polyphagy more commonly than butterfly caterpillars. Perhaps more intriguing, carnivorous caterpillars exist in tropical regions of the world and feed on other arthropods like flies and other caterpillars. Some are even known to feed on ants and their larvae by using chemical cues to fool the eusocial insects into thinking they are part of the colony. There are also detritivorous caterpillars.
Above: Caterpillars exist to eat. Here, Plain Tiger (Danaus chrysippus chrysippus) caterpillars are dining on one of their host plants, the Crown flower (Calotropis gigantea).
Relationship with humans
Many caterpillars are considered pests, due to their relentless herbivorous feeding habits. For example, the tomato hornworm which refers to the caterpillar of the hawk moth Manduca quinquemaculata, is a huge pest of tomato plants in the United States. Locally, the lime butterfly, Papilio demoleus, is considered a pest of lime plants.
Many caterpillars are also known to possess irritating toxic hairs, which can cause allergic attacks in humans. Some can cause fatal attacks, such as Lonomia obliqua, the Giant Silkworm Moth, of South America.
However, despite the undesirability of most caterpillars, the adult butterflies are important pollinators of plants. Furthermore, butterflies often attract curious people with their bright colours. As a result, butterfly gardens are not an uncommon sight in Singapore.
Lepidopterans also provide other important services for humans. The silk moth, Bombyx mori, is popular for providing silk which we humans use to make clothes. Entomophagy, or the consumption of insects, also features Lepidopterans; silkworm pupae are eaten in some cultures.
Above: The caterpillar of the lime butterfly, Papilio demoleus malayanus. This little critter has a voracious appetite for lime leaves.
Notable families
1) Tineidae (Fungus moths)
These moths are relatively inconspicuous, many are tiny and easily missed. Most Tineid moths are detritivorous, an oddity among Lepidopterans. The casebearer moth, Phereoeca uterella, is common in households in Singapore, with its distinctive case that resembles a pumpkin seed.
2) Sphingidae (Hawk moths)
These relatively large moths can be mistaken for larger bees like carpenter bees. Their flight movements are pretty distinct, and many have unique or spectacular colouration. Larvae are often host specific, unlike many other moths. They are strong fliers, and rapidly move from flower to flower, with some species known to hover in flight. In Singapore, perhaps the most attractive hawk moth species is Daphnis nerii, the Oleander Hawk Moth, with its elaborate green patterns. This species' caterpillars feed on plants such as Catharanthus roseus, the Madagascan Periwinkle. Other Sphingidae in Singapore include the Hummingbird Hawk Moth, Macroglossum stellatarum, a diurnal species, as well as Acherontia styx, the Bee robber, which feeds on honey directly from bee hives.
3) Erebidae (Tussock moths)
The caterpillars of this family of moths often have very striking colours and are very hairy. Some of them can cause severe irritations in humans if handled, and as such should be left alone. The adult tussock moths are often drab and seemingly uninteresting, but colourful ones can be found too. Amata huebneri, the Tiger moth, is likely the most commonly encountered tussock moth in Singapore. Other tussock moths seen in Singapore are Chalciope mygdon (Triangular moth) and Hypopyra pudens.
Above: Calliteara horsfieldii, the yellow caterpillar of this tussock moth is just an example of how a typical Erebidae caterpillar looks like.
4) Tortricidae (Leafroller moths)
Totricid moths are commonly regarded as pests, as their larvae feed on a variety of economically important food plants, such as apples, peaches and raspberry. In Singapore, Phricanthes flexilineana is a native species.
5) Geometridae (Geometer moths)
The caterpillars of these moths are known as inchworms, and while most feed on leaves, there are pollen, lichen, flower feeders too. The genus Eupithecia contains carnivorous caterpillars even. In Singapore, Traminda mundissima and Dysphania malayanus are two native Geometrid moths.
6) Saturniidae (Royal moths)
The world's largest Lepidopteran, Attacus atlas (Atlas moth) is from this family. The famous Actias luna (Luna moth) is also a Saturniid moth. The caterpillars are large, some are equipped with hairs that can cause irritation or even death in humans. The deadly caterpillar of Lonomia obliqua is one such example. Locally, Attacus atlas can still be found.
7) Bombycidae (Silk moths)
The silkworm moth, Bombyx mori, is found in this family. Otherwise pretty generic looking moths, a local species is Gunda subnotata.
8) Hesperiidae (Skippers)
The skippers are regarded to be more closely related to butterflies than to moths, even though they share characteristics of both. Identification is done through their antennae, which form hooked tips rather than the clubs of typical butterflies. They are speedy fliers, and often dart around quickly to evade predators. Iambrix salsala (Chestnut Bob), Odina hieroglyphica (Hieroglyphic Flat) and Plastingia naga (Chequered Lancer) are three skippers species found in Singapore.
9) Papilionidae (Swallowtail butterflies)
These butterflies often have protrusions on their hind wings, which give them their names. The largest butterflies are from this family; Ornithoptera alexandrae (Queen Alexandra's Birdwing) is the largest butterfly in the world. Caterpillars of this family have an organ known as an osmeterium, which is a pink 'tongue' that emits a nasty odour when the caterpillar is threatened. Singaporean species include Papilio demoleus malayanus (Lime butterfly), Papilio polytes romulus (Common Mormon), Chilasa clytia clytia (Common Mime) and Pathysa antiphates itamputi (Five Bar Swordtail).
Above: A female Common Mormon (Papilio polytes romulus). A commonly encountered species in Singapore, even in urban areas.
10) Nymphalidae (Brush-footed butterflies)
The largest family of butterflies, the Nymphalidae contain familiar species like the Monarch butterfly, Danaus plexippus. They are often colourful when viewed from above, while their ventral sides are frequently rather drab. In Singapore, Junonia hedonia ida (Chocolate Pansy), Junonia almana javana (Peacock Pansy), Danaus chrysippus chrysippus (Plain Tiger), Tanaecia iapis puseda (Horsfield's Baron) and Junonia orithya wallacei (Blue Pansy) are some of the more commonly encountered Nymphalids.
Above: The Chocolate Pansy (Junonia hedonia ida) is one of the commonest butterfly species found in Singapore.
Below: The Tawny coster (Acraea terpsicore) was first recorded in Singapore in 2006. Today, it is found island wide, wherever its host plant, the stinking passionflower (Passiflora foetida) is cultivated.
11) Uraniidae (Sunset moths)
Sunset moths contain many diurnal species, unlike most moths. Their bright colours make them easily mistaken for butterflies. Lyssa zampa (Tropical swallowtail moth) and Acropteris rectinervata are two sunset moth species found in Singapore.
12) Lycaenidae (Gossamer-winged butterflies)
The second largest family of butterflies (after Nymphalidae), the adults are typically small, and the larvae of some species are known to feed on aphids, scale insects and ant larvae. Many are associated with ants in some regard, and this successful family is extremely diverse in terms of feeding habits. Lycaenids found in Singapore include Chilades pandava pandava (Cycad Blue), Zizula hylax pygmaea (Pygymy Grass Blue) and Logania marmorata damis (Pale Mottle); the latter is known to feed on aphids in its larval stage.
Some Lepidopterans on Instagram:
Above: An unknown tussock moth caterpillar (Erebidae). Fluffy looking creature.